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Old 04-12-2009, 09:48 AM   #1
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Default LiPo charging dilema

Hey folks, I put a post about this in the Radio and Electronics section an got zero replies, so I'll try here.

I've recently switched over from NiMh batteries to LiPo. I have just received my first 2S battery packs and made an interesting discovery. I have an IMAX B8 balance charger. This is the biggest baddest version of the IMAX series. The problem is, even though the specs say will charge from 1S to 8S, it only has balance ports from 3S to 8S.

I know that you can custom make cables to charge multiple batteries at once, so I guess what I need to do is to use the 4S balance port and build a cable that will split into two 2S ports. And I'd need to build a cable from the charging cable that would split to the charge plugs on BOTH of the batteries.

Can anybody help me with the proper wiring pattern that I would need to use? I don't want to damage either the batteries or the charger. I'm guessing that the charge cable would need to have both plugs wired in series so the charger would see the two 2S as a single 4S battery, correct? I'm not certain how to do the balance side though.

Any help would be appreciated. I have several new hardcase 2S LiPo's just sitting here and I'm anxious to put them to work.
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Old 04-12-2009, 10:16 AM   #2
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Default lipos

My answer for that question - DON'T!

If you can't buy what you need, then don't mess about with lipos, they're just too dangerous if something goes wrong.
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Old 04-12-2009, 10:44 AM   #3
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Quote:
Originally Posted by sldmodels View Post
My answer for that question - DON'T!

If you can't buy what you need, then don't mess about with lipos, they're just too dangerous if something goes wrong.
The only way LiPo's are dangerous are if they are over charged. Then yes they are a bomb waiting to happen. But I KNOW that this can be done correctly, and comapnies like HobbyKing even SELL some of these cables. Problem is I can find a 6S to two 3S. but not a 4S to two 2S splitter. If the wireing is correct, the charger will treat the setup as a single 4S battery and all of the safeguards that the charger has built in will work properly. That's why I'm asking for help from others who may have run into this before. I'm not a 14 year old playing with electricity for the first time, but an electrical engineer who has worked with circuits for over 30 years. I just want to get it right the first time.

Here's an example of an available cable: http://www.hobbycity.com/hobbycity/s...litter(JST-XH)
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Old 04-12-2009, 01:23 PM   #4
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Just had a look at Much-More's website, as I was thinking they're more likely to do them, but thinking about it, maybe you can't get a 4 and 2, and the reason you can get a 6 to 3 and 3 is that it's easier to just split the power evenly over the lipos (if my phrasing of that makes sense), although, a good enough charger should be able to "sense" how many cells are in a lipo, which you say yours should be.
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Old 04-12-2009, 02:42 PM   #5
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Why not just buy a dual output Hyperion if you want to charge more than one pack at a time? It may not be the biggest and baddest, but it IS made to charge multiple packs at the same time.
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Old 04-12-2009, 02:49 PM   #6
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Why not just buy a dual output Hyperion if you want to charge more than one pack at a time? It may not be the biggest and baddest, but it IS made to charge multiple packs at the same time.
I don't really care about charging multiple batteries. The problem is that the charger I have doesn't have a balance plug for 2S LiPo's. If I need to charge them 2 at a time I can do that. I just don't want to have to buy YET ANOTHER charger.
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Old 04-12-2009, 03:14 PM   #7
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Sorry, I misunderstood your intent.

You should be able to charge and balance a 2S pack using the 3S balance port... if there are only two cells present it should just ignore the "missing" third cell.

My Thunder Power 610 worked that way... I made my balance lead from a 3S lead and everything worked fine with 2S packs.

Here's a pic of the charge/balance cord I made for the Thunder Power 610 charger... my LiPO packs had a large banana port at the positive and negative terminal, and a small 2mm banana port in the middle for the balancer. I used the Thunder Power 3S balance harness to make this up. Used the Black, white, and blue wires of the balance lead, and I cut the red wire at the plug since it wasn't needed with 2S packs. Hope this is helpful...
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Old 04-12-2009, 11:36 PM   #8
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Quote:
Originally Posted by Trips View Post
Sorry, I misunderstood your intent.

You should be able to charge and balance a 2S pack using the 3S balance port... if there are only two cells present it should just ignore the "missing" third cell.

My Thunder Power 610 worked that way... I made my balance lead from a 3S lead and everything worked fine with 2S packs.

Here's a pic of the charge/balance cord I made for the Thunder Power 610 charger... my LiPO packs had a large banana port at the positive and negative terminal, and a small 2mm banana port in the middle for the balancer. I used the Thunder Power 3S balance harness to make this up. Used the Black, white, and blue wires of the balance lead, and I cut the red wire at the plug since it wasn't needed with 2S packs. Hope this is helpful...
That's exactly what I need. I just didn't know that I could use the 3S port with a 2S wiring pattern. That will be easy to do. Thanks
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